It is now commonly accepted that the vision imparing disease known as cataracts can be alleviated by surgically replacing the natural lens of the eye with an artificial intraocular lens.
The anatomy of the eye 1 is shown schematically in FIG. 1B. The cornea 2 forms the front surface of the eye and connects with the ciliary muscle 3 from which the iris 4 extends. Iris 4 divides the front portion of the eye into the anterior chamber 5 between the iris 4 and the cornea 2 and the posterior chamber 6 behind the iris. Pupil 8 is the aperture in the center of the iris through which light passes to the posterior chamber and to the back of the eye (not shown). Pupil 8 enlarges and contracts as iris 4 changes size in response to light impinging upon the iris tissue. The natural lens of the eye (not shown) is removed during cataract surgery leaving, in certain circumstances, the capsular bag 10 in place. Suspensary ligaments 12, also known as zonules support capsular bag 10 in posterior chamber 6 of the eye extending from the periphery of capsular bag 10 to the surrounding ciliary muscle 3.
An intraocular lens may be inserted in the eye by a variety of well known surgical techniques. A representative intraocular lens is shown in the eye in FIGS. 1A and 1B. An intraocular lens has two principal parts: a medial light-focusing body 20 (also called the optic) made of non-toxic plastic material which will replace the natural lens of the eye and focus light on the retina: and haptic support portions 18, 19 which extend from optic 20 to the anatomy of the eye and provide a means for fixing and holding optic 20 in its proper position within the eye.
Many surgical procedures of choice require that the lens be manipulated during the insertion. In the past positioning holes 14 have been used for that purpose. A surgical instrument 15, often called a hook, is inserted through an incision 16 into the eye. The end of the hook is placed into hole 14 which in the past has been drilled completely through optic 20 generally in a direction parallel to the optical axis of optic 20. Once hook 15 is inserted into positioning hole 14, the lens may be maneuvered as desired by the surgeon.
It has been found that positioning holes of intraocular lens optics cause certain amount of glare and glitter. This is particularly troublesome during the evening when the iris of the eye is open to a larger extent than it is during the day and consequently the pupil 8 is larger than usual. Thus, at night, even when the lens is placed in posterior chamber 6 behind iris 4, the positioning holes can be in the path of light between the cornea and retina. It would be desirable to have an intraocular lens which provided positioning holes for the use of the surgeon during insertion of the lens but on which the positioning holes did not cause additional glare and glitter for the patient after the lens is inserted.